Angewandte Chemie International Edition

Cover image for Vol. 46 Issue 36

September 10, 2007

Volume 46, Issue 36

Pages 6741–6931

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Obituary
    9. Highlights
    10. Essay
    11. Review
    12. Communications
    13. Correspondence
    14. Preview
    1. Cover Picture: Tandem Si[BOND]C and C[BOND]H Activation for Decamethylhafnocene and Bis(trimethylsilyl)acetylene (Angew. Chem. Int. Ed. 36/2007) (page 6741)

      Torsten Beweries, Vladimir V. Burlakov, Marc A. Bach, Stephan Peitz, Perdita Arndt, Wolfgang Baumann, Anke Spannenberg, Uwe Rosenthal, Biswarup Pathak and Eluvathingal D. Jemmis

      Version of Record online: 4 SEP 2007 | DOI: 10.1002/anie.200790176

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      Only hafnium but not titanium and zirconium promote simultaneous Si[BOND]C and C[BOND]H bond-cleavage reactions of bis(trimethylsilyl)acetylene that occur by interaction with decamethyl metallocene. In their Communication on page 6907 ff., U. Rosenthal, E. D. Jemmis, and co-workers investigate this reaction, which exemplifies the higher reactivity of hafnocenes relative to their titanocene and zirconocene congeners. The cover picture shows the corresponding section of the periodic table, in which red indicates the unexpected activity of hafnium.

  2. Inside Cover

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Obituary
    9. Highlights
    10. Essay
    11. Review
    12. Communications
    13. Correspondence
    14. Preview
    1. Inside Cover: Facile Preparation of Complex Protein Architectures with Sub-100-nm Resolution on Surfaces (Angew. Chem. Int. Ed. 36/2007) (page 6742)

      Sean R. Coyer, Andrés J. García and Emmanuel Delamarche

      Version of Record online: 4 SEP 2007 | DOI: 10.1002/anie.200790177

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      Multiple proteins are simultaneously patterned into complex architectures by a novel method, as reported by E. Delamarche and co-workers in their Communication on page 6837 ff. This method involves three elementary steps: inking of proteins onto an elastomer, subtracting the proteins to form a pattern by using a nanotemplate, and printing the remaining proteins onto the substrate. Combining and repeating these steps allows the patterning of proteins on surfaces with arbitrary patterns and a resolution better than 100 nm.

  3. Editorial

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Obituary
    9. Highlights
    10. Essay
    11. Review
    12. Communications
    13. Correspondence
    14. Preview
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  4. Graphical Abstract

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Obituary
    9. Highlights
    10. Essay
    11. Review
    12. Communications
    13. Correspondence
    14. Preview
  5. News

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Obituary
    9. Highlights
    10. Essay
    11. Review
    12. Communications
    13. Correspondence
    14. Preview
  6. Book Review

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Obituary
    9. Highlights
    10. Essay
    11. Review
    12. Communications
    13. Correspondence
    14. Preview
  7. Obituary

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Obituary
    9. Highlights
    10. Essay
    11. Review
    12. Communications
    13. Correspondence
    14. Preview
    1. A. Ian Scott (1928–2007) (page 6768)

      Peter Shoolingin-Jordan

      Version of Record online: 4 SEP 2007 | DOI: 10.1002/anie.200703300

  8. Highlights

    1. Top of page
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    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Obituary
    9. Highlights
    10. Essay
    11. Review
    12. Communications
    13. Correspondence
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      Hafnium: Stepping into the Limelight! (pages 6770–6771)

      Christoph Marschner

      Version of Record online: 22 AUG 2007 | DOI: 10.1002/anie.200702573

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      Worth the wait! Hafnium, a largely underrated element, showed unexpected C[BOND]H and Si[BOND]C bond activation chemistry, which was found during the course of the first synthesis of hafniumbis(silyl)alkyne complexes. As for the case of N2-activation, hafnium proves to be superior to zirconium in this respect.

    2. The Fatty Acid Factory of Yeasts (pages 6772–6775)

      Thomas Kolter

      Version of Record online: 9 AUG 2007 | DOI: 10.1002/anie.200702930

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      Fatty acids are essential metabolites for nearly all organisms. Yeasts, fungi, and animals synthesize them using fatty acid synthases of type I (FAS I) in the cytoplasm, whereby the FAS I of animals is distinct from that of fungi and yeasts. Recently obtained high-resolution X-ray structures of the 2.6-MDa FAS enzyme from yeast and fungi (see picture) now allow a closer look at the mechanism of this reaction.

  9. Essay

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Obituary
    9. Highlights
    10. Essay
    11. Review
    12. Communications
    13. Correspondence
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      Centenary of the Award of a Nobel Prize to Eduard Buchner, the Father of Biochemistry in a Test Tube and Thus of Experimental Molecular Bioscience (pages 6776–6782)

      Lothar Jaenicke

      Version of Record online: 28 JUN 2007 | DOI: 10.1002/anie.200700390

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      The discovery of cell-free alcohol fermentation: In 1897 Eduard Buchner laid the foundation stone for modern in vitro enzymology from his studies on the conversion of sugar into ethanol in the presence of zymase derived from yeast. The resulting Nobel Prize in Chemistry was awarded to Buchner one hundred years ago in 1907.

  10. Review

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Obituary
    9. Highlights
    10. Essay
    11. Review
    12. Communications
    13. Correspondence
    14. Preview
    1. Sustainable Concepts in Olefin Metathesis (pages 6786–6801)

      Hervé Clavier, Karol Grela, Andreas Kirschning, Marc Mauduit and Steven P. Nolan

      Version of Record online: 19 JUL 2007 | DOI: 10.1002/anie.200605099

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      Thinking green: One of the challenging goals of modern chemistry is the development of clean and environmentally friendly processes, particularly as the number of transition-metal-catalyzed processes is increasing. With the example of ruthenium-catalyzed olefin metathesis, a comprehensive and critical overview is provided of the recent progress achieved in this area.

  11. Communications

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Obituary
    9. Highlights
    10. Essay
    11. Review
    12. Communications
    13. Correspondence
    14. Preview
    1. Molecularly Defined Shape-Persistent 2D Oligomers: The Covalent-Template Approach to Molecular Spoked Wheels (pages 6802–6806)

      Dennis Mössinger, Jens Hornung, Shengbin Lei, Steven De Feyter and Sigurd Höger

      Version of Record online: 26 JUN 2007 | DOI: 10.1002/anie.200701614

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      A template-directed sixfold dimerization of alkyne units is the final step in the synthesis of the title compound leading to nanoscale 2D rigid wheel-shaped oligo(phenylene ethynylene)s. Solubilizing side groups allow full characterization by NMR spectroscopy, GPC, MALDI-TOF MS, and STM. The distance between two peripheral tert-butyl groups at opposite sites of the oligomer is estimated to be 7 nm.

    2. Self-Assembly of T-Shaped Aromatic Amphiphiles into Stimulus-Responsive Nanofibers (pages 6807–6810)

      Kyung-Soo Moon, Ho-Joong Kim, Eunji Lee and Myongsoo Lee

      Version of Record online: 2 AUG 2007 | DOI: 10.1002/anie.200702136

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      Stimulating fibers: Self-assembled nanofibers coated with hydrophilic oligo(ethylene oxide) dendrons transform reversibly, upon heating, into hydrophobic nanofiber bundles as a result of dehydration of the dendritic chains (see scheme). A thermoresponsive sol–gel phase transition is observed.

    3. Deprotonation Mechanism of NH4+ in the Escherichia coli Ammonium Transporter AmtB: Insight from QM and QM/MM Calculations (pages 6811–6815)

      Zexing Cao, Yirong Mo and Walter Thiel

      Version of Record online: 2 AUG 2007 | DOI: 10.1002/anie.200701348

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      All wired up: In the ammonia-channel protein AmtB, the deprotonation of NH4+ can occur along a hydrogen-bond wire that contains two water molecules and terminates at the proton acceptor, the carboxylate group of the residue Asp160 (see picture). The results of quantum-mechanical and quantum-mechanical/molecular-mechanical calculations suggest that a stepwise rather than a concerted mechanism is involved.

    4. Protein Kinase Assay on Peptide-Conjugated Gold Nanoparticles by Using Secondary-Ion Mass Spectrometric Imaging (pages 6816–6819)

      Young-Pil Kim, Eunkeu Oh, Young-Hee Oh, Dae Won Moon, Tae Geol Lee and Hak-Sung Kim

      Version of Record online: 30 JUL 2007 | DOI: 10.1002/anie.200701418

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      Spot the mass of peptides: A label-free protein kinase assay that uses secondary-ion mass spectrometric imaging has been demonstrated with peptide-conjugated gold nanoparticles (AuNPs). With detection of the mass change of peptide substrates in a kinase reaction, AuNP-enhanced peptide signals enabled the assaying of both the protein kinase and its inhibition by chemical imaging of peptide substrates on a surface (see picture).

    5. Molecule-Based Ferroelectric Thin Films: Mononuclear Lanthanide Enantiomers Displaying Room-Temperature Ferroelectric and Dielectric Properties (pages 6820–6823)

      Xi-Li Li, Kai Chen, Yu Liu, Zhao-Xi Wang, Tian-Wei Wang, Jing-Lin Zuo, Yi-Zhi Li, Yue Wang, Jin Song Zhu, Jun-Min Liu, You Song and Xiao-Zeng You

      Version of Record online: 2 AUG 2007 | DOI: 10.1002/anie.200701802

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      Eu-reka! Two neutral mononuclear europium enantiomers [Eu(tta)3L] and their thin films were prepared (tta=2-thenoyltrifluoroacetonate; L=(−)-4,5-pinene bipyridine (1), L=(+)-4,5-pinene bipyridine (2)). The ferroelectric measurements of the thin films show EP hysteresis loops at room temperature (Tc=28.0 °C) with remnant polarization of 0.022 μC cm−2 and a coercive field of 25 kV cm−1.

    6. Synthesis of Highly Fluorescent Gold Nanoparticles for Sensing Mercury(II) (pages 6824–6828)

      Chih-Ching Huang, Zusing Yang, Kun-Hong Lee and Huan-Tsung Chang

      Version of Record online: 2 AUG 2007 | DOI: 10.1002/anie.200700803

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      Quenching upon aggregation: 11-Mercaptoundecanoic acid (11-MUA)-protected Au nanoparticles (11-MUA-AuNPs) are much more stable and fluoresce much more strongly than the corresponding unmodified AuNPs. After addition of 2,6-pyridinedicarboxylic acid, the 11-MUA-AuNPs bind to HgII with both high sensitivity and selectivity.

    7. Formation of Titania/Silica Hybrid Nanowires Containing Linear Mesocage Arrays by Evaporation-Induced Block-Copolymer Self-Assembly and Atomic Layer Deposition (pages 6829–6832)

      Xin Chen, Mato Knez, Andreas Berger, Kornelius Nielsch, Ulrich Gösele and Martin Steinhart

      Version of Record online: 2 AUG 2007 | DOI: 10.1002/anie.200700923

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      Hot-wired silica: Titania-functionalized silica nanowires containing linear arrays of mesocages (see picture) are prepared by a combination of evaporation-induced self-assembly of polystyrene-block-poly(ethylene oxide) soft templates inside nanoporous hard templates and atomic layer deposition. This combination allows the independent tuning of the internal fine structure of the nanowires and the properties of their outer surface.

    8. A Minimal Protein Folding Model To Measure Hydrophobic and CH–π Effects on Interactions between Nonpolar Surfaces in Water (pages 6833–6836)

      Brijesh Bhayana and Craig S. Wilcox

      Version of Record online: 3 AUG 2007 | DOI: 10.1002/anie.200700932

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      In the balance: A synthetic molecule that exhibits two-state folding behavior in water is described. Quantitative experiments reveal that the microscopic hydrophobic effect is similar in magnitude to the CH–π interaction. These forces may therefore be equally important in the folding of aromatic-rich regions of proteins. The method allows a new approach to the direct measurement of excess surface energy associated with nonpolar surfaces.

    9. Facile Preparation of Complex Protein Architectures with Sub-100-nm Resolution on Surfaces (pages 6837–6840)

      Sean R. Coyer, Andrés J. García and Emmanuel Delamarche

      Version of Record online: 19 JUN 2007 | DOI: 10.1002/anie.200700989

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      Ink, subtract, print: A novel method is developed for patterning proteins into complex architectures with high resolution, high contrast, and self-alignment (see fluorescence micrographs). An elastomer is inked with proteins, and a nanotemplate is used to selectively subtract proteins, leaving a pattern that is then printed onto a substrate.

    10. Mimicry of Polyketide Synthases—Enantioselective 1,4-Addition Reactions of Malonic Acid Half-Thioesters to Nitroolefins (pages 6841–6844)

      Jana Lubkoll and Helma Wennemers

      Version of Record online: 6 AUG 2007 | DOI: 10.1002/anie.200702187

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      Bifunctionality is the key for mimicking the active site of polyketide synthases with synthetic metal-free organocatalysts (see picture). Cinchona alkaloid derivatives bearing both a basic site and a urea moiety catalyze conjugate enantioselective addition reactions of malonic acid half thioesters (MAHTs) to nitroolefins with up to quantitative yields and selectivities up to 90 % ee.

    11. Solid-Phase Synthesis of Oligo(phenylene ethynylene) Rotaxanes (pages 6845–6848)

      Heather W. Daniell, Eric J. F. Klotz, Barbara Odell, Tim D. W. Claridge and Harry L. Anderson

      Version of Record online: 2 AUG 2007 | DOI: 10.1002/anie.200702349

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      Hooks and feelers: The use of a bulky tripod-shaped stopper as a solid-phase attachment point proves essential for the controlled iterative solid-phase synthesis of an α-cyclodextrin [3]rotaxane (see picture). NMR spectroscopy confirms the structure and shows that both the cyclodextrin units have well-defined locations and orientations.

    12. A Biosynthetic Route to Dehydroalanine-Containing Proteins (pages 6849–6851)

      Jiangyun Wang, Stefan M. Schiller and Peter G. Schultz

      Version of Record online: 8 AUG 2007 | DOI: 10.1002/anie.200702305

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      It's not natural: The nonnatural amino acid phenylselenocysteine has been genetically incorporated into proteins in E. coli in response to the amber nonsense codon TAG. Oxidative elimination followed by Michael addition led to incorporation of (S)-hexadecyl- and (S)-mannosylcysteine into green fluorescent protein. This approach provides a useful method to modify protein side chains and backbone structures.

    13. Large Anisotropy and Effect of Deuteration on Permittivity in an Olefin Copper(I) Complex (pages 6852–6856)

      Qiong Ye, Hong Zhao, Zhi-Rong Qu, Da-Wei Fu, Ren-Gen Xiong, Yi-Ping Cui, Tomoyuki Akutagawa, Philip Wai Hong Chan and Takayoshi Nakamura

      Version of Record online: 2 AUG 2007 | DOI: 10.1002/anie.200700629

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      Different directions: Huge and permanent anisotropy (see picture, left) was observed in an olefin copper complex (see structural formula, right). This phenomenon is likely due to weak D⋅⋅⋅Br interactions in the crystal.

    14. Implementation of a Temperature-Gradient Reactor System for High-Throughput Investigation of Phosphonate-Based Inorganic–Organic Hybrid Compounds (pages 6857–6860)

      Sebastian Bauer and Norbert Stock

      Version of Record online: 3 AUG 2007 | DOI: 10.1002/anie.200701575

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      Five new Cd phosphonates were discovered in a systematic investigation of the influence of the reaction temperature besides composition and pH value on the synthesis of inorganic–organic hybrid compounds in the CdCl2/H5L/NaOH system, which was achieved by the title procedure. In the resulting crystallization diagram (see picture), each color corresponds to a different phase.

    15. Enhanced Cooperative Activation Effect in the Hydrolytic Kinetic Resolution of Epoxides on [Co(salen)] Catalysts Confined in Nanocages (pages 6861–6865)

      Hengquan Yang, Lei Zhang, Lin Zhong, Qihua Yang and Can Li

      Version of Record online: 31 JUL 2007 | DOI: 10.1002/anie.200701747

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      Being cagey: More than two chiral [Co(salen)] catalyst molecules can be confined in one nanocage of SBA-16 by reducing the pore entrance size by silylation. The [Co(salen)]/SBA-16 catalysts with more than two [Co(salen)] complexes in each cage show a significantly enhanced cooperative activation effect and exhibit much higher activity than the homogeneous [Co(salen)] catalyst in the hydrolytic kinetic resolution of epoxides (see scheme).

    16. Crossed-Molecular-Beam Study on the Formation of Phenylacetylene from Phenyl Radicals and Acetylene (pages 6866–6869)

      Xibin Gu, Fangtong Zhang, Ying Guo and Ralf I. Kaiser

      Version of Record online: 19 JUL 2007 | DOI: 10.1002/anie.200701890

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      A hot topic! Crossed-molecular-beam experiments showed that phenylacetylene molecules—precursors to polycyclic aromatic hydrocarbons in combustion flames and in carbon-rich planetary nebulae—can be formed through reactions of phenyl radicals with acetylene under single-collision conditions (see picture).

    17. Access to Guaianolides: Highly Efficient Stereocontrolled Total Synthesis of (±)-Geigerin (pages 6870–6873)

      Sébastien Carret and Jean-Pierre Deprés

      Version of Record online: 3 AUG 2007 | DOI: 10.1002/anie.200702031

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      Geiger counter: The first total synthesis of geigerin (3), a member of the guaian-8,12-olides, has been achieved in eight regio- and stereocontrolled steps from the tropylium cation. En route, the guaian-6,12-olide 2 is formed in two steps from the hydroazulenone 1, a versatile intermediate.

    18. Electrophile-Induced Ether Transfer: Stereoselective Synthesis of 2,4,6-Trisubstituted Tetrahydropyrans (pages 6874–6877)

      Rendy Kartika and Richard E. Taylor

      Version of Record online: 2 AUG 2007 | DOI: 10.1002/anie.200702018

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      A negative attack: Synthesis of 4-alkoxy-2,6-cis- and its stereocomplementary 4-alkoxy-2,6-trans-tetrahydropyrans has been achieved in high yield and with excellent stereocontrol by a common strategy: electrophile-induced ether-transfer, cyclization, and functionalization reactions (see scheme; Bn=benzyl; BPS=tert-butyldiphenylsilyl; TBS=tert-butyldimethylsilyl; TEA=triethylamine).

    19. Structural Changes Accompanying the Stepwise Population of a B[BOND]C π Bond (pages 6878–6881)

      Ching-Wen Chiu and François P. Gabbaï

      Version of Record online: 6 AUG 2007 | DOI: 10.1002/anie.200702299

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      Get Shorty: The central boron–carbon bond of an α-borylated carbocation undergoes a noticeable shortening upon reduction by one and two electrons, and the degree of twisting about this bond is also noticeably reduced (see graph). According to both experiment and theory, these effects result from the sequential population of the central boron–carbon π bond.

    20. Organocatalytic Asymmetric α-Selenenylation of Aldehydes (pages 6882–6885)

      Marcello Tiecco, Armando Carlone, Silvia Sternativo, Francesca Marini, Giuseppe Bartoli and Paolo Melchiorre

      Version of Record online: 6 AUG 2007 | DOI: 10.1002/anie.200702318

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      Getting round the (periodic) table: The enamine activation concept has been extended to the asymmetric addition of selenium-based compounds to aldehydes in an organocatalytic transformation that provides high reaction efficiency and stereocontrol (ee values ranging from 95 to 99 %) with readily available chiral secondary amines. The chiral α-seleno aldehydes thus formed can be used as versatile intermediates .

    21. Specific DNA Recognition by a Synthetic, Monomeric Cys2His2 Zinc-Finger Peptide Conjugated to a Minor-Groove Binder (pages 6886–6890)

      Olalla Vázquez, M. Eugenio Vázquez, Juan B. Blanco, Luis Castedo and José L. Mascareñas

      Version of Record online: 2 AUG 2007 | DOI: 10.1002/anie.200702345

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      Wrapped around the finger: Tailored Cys2His2 zinc-finger domains can specifically bind to DNA when assisted by minor-groove accessory interactions. In this way, appropriately designed hybrids containing the zinc-finger unit of the GAGA factor and a distamycin-like tripyrrole bind with high affinity to DNA sites that have a GAG triad near the 3′ side of an A-rich fragment.

    22. Selective One-Pot Carbon–Carbon Bond Formation by Catalytic Boronation of Unactivated Cycloalkenes and Subsequent Coupling (pages 6891–6893)

      Vilhelm J. Olsson and Kálmán J. Szabó

      Version of Record online: 2 AUG 2007 | DOI: 10.1002/anie.200702499

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      Two channels: Cycloalkenes can be selectively functionalized by iridium-catalyzed boronation followed by Suzuki coupling with an aryl iodide or reaction with an aldehyde. The selectivity for allylic and vinylic functionalization can be controlled by a slight change of the reaction conditions. DBU=1,8-diazabicyclo[5.4.0]undec-7-ene, pin=pinacol.

    23. The Thermal Retro[2+2+2]cycloaddition of Cyclohexane Activated by Triscyclobutenannelation: Concerted All-Disrotatory versus Stepwise Conrotatory Pathways to Fused [12]Annulenes (pages 6894–6898)

      Michael J. Eichberg, K. N. Houk, Jürg Lehmann, Philip W. Leonard, Anne Märker, Joseph E. Norton, Dorota Sawicka, K. Peter C. Vollhardt, Glenn D. Whitener and Stefan Wolff

      Version of Record online: 7 AUG 2007 | DOI: 10.1002/anie.200702474

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      All dis or all con? While benzo analogues 24 undergo cycloreversion of the central cyclohexane ring by all-disrotatory opening, the triscyclobutenocyclohexane 1 does so by stepwise conrotatory cyclobutane rupture. This remarkable conclusion is based on DFT calculations carried out in conjunction with experiments.

    24. Modular Synthesis of Radicicol A and Related Resorcylic Acid Lactones, Potent Kinase Inhibitors (pages 6899–6902)

      Pierre-Yves Dakas, Sofia Barluenga, Frank Totzke, Ute Zirrgiebel and Nicolas Winssinger

      Version of Record online: 3 AUG 2007 | DOI: 10.1002/anie.200702406

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      Short and sweet: A concise and modular synthesis of radicicol A and related resorcylic acid lactones using fluorous isolation technology and immobilized reagents is reported (see scheme, RF=C3H6C6F13, TMSE=2-(trimethylsilyl)ethyl). The compounds are found to be potent (low-nanomolar) inhibitors of selected kinases. Despite their irreversible inactivation of kinases, they show good selectivity amongst a panel of 127 kinases.

    25. Dual Catalysis: A Combined Enantioselective Brønsted Acid and Metal-Catalyzed Reaction—Metal Catalysis with Chiral Counterions (pages 6903–6906)

      Magnus Rueping, Andrey P. Antonchick and Claus Brinkmann

      Version of Record online: 10 AUG 2007 | DOI: 10.1002/anie.200702439

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      Double take: The combination of enantioselective Brønsted acid catalyzed activation and metal-catalyzed alkynylation of α-imino esters under mild reaction conditions leads to amino acids in high yields and with excellent e.r. values (see scheme; PG=protecting group).

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      Tandem Si[BOND]C and C[BOND]H Activation for Decamethylhafnocene and Bis(trimethylsilyl)acetylene (pages 6907–6910)

      Torsten Beweries, Vladimir V. Burlakov, Marc A. Bach, Stephan Peitz, Perdita Arndt, Wolfgang Baumann, Anke Spannenberg, Uwe Rosenthal, Biswarup Pathak and Eluvathingal D. Jemmis

      Version of Record online: 6 JUL 2007 | DOI: 10.1002/anie.200701565

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      Hafnium's triumph over titanium and zirconium! Unusual tandem Si[BOND]C and C[BOND]H bond activations by hafnium to form the alkenyl complex 2 and the silahafnacyclopentene 3 were observed in the reaction of decamethylhafnocene and bis(trimethylsilyl)acetylene. The higher reactivity of hafnocene compounds relative to their titanocene and zirconocene congeners is of general importance for synthesis and catalytic applications.

    27. Elucidation of Nonstatistical Dynamic Effects in the Cyclization of Enyne Allenes by Means of Kinetic Isotope Effects (pages 6911–6914)

      Michael Schmittel, Chandrasekhar Vavilala and Ralph Jaquet

      Version of Record online: 6 AUG 2007 | DOI: 10.1002/anie.200700709

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      In no man's land—a reaction without a classic mechanism: A series of enyne allenes follow neither the classical concerted nor stepwise mechanism but rather comply with dynamic nonstatistical laws. The computed potential energy surface (see figure) and experimental kinetic isotope effects indicate that dynamic effects operate before as well as after the transition state.

    28. Electrospray Ionization Mass Spectrometric Study on the Direct Organocatalytic α-Halogenation of Aldehydes (pages 6915–6917)

      Cesar A. Marquez, Francesco Fabbretti and Jürgen O. Metzger

      Version of Record online: 7 AUG 2007 | DOI: 10.1002/anie.200700266

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      Halide effects: A mechanistic study on the L-prolineamide-catalyzed α-halogenation of butanal 1 by ESI-MS has enabled the direct detection of the most important intermediates in the catalysis cycle, including the reactive N[BOND]Cl intermediate (T2 in scheme). In contrast, the reaction with N-bromo- and N-iodosuccinimide occurs by direct C halogenation.

    29. Dynamics and Infrared Spectroscopy of the Protonated Water Dimer (pages 6918–6921)

      Oriol Vendrell, Fabien Gatti and Hans-Dieter Meyer

      Version of Record online: 3 AUG 2007 | DOI: 10.1002/anie.200702201

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      Coupling shakes this couple: Dynamics and the IR absorption spectrum of the protonated water dimer are reported by full-dimensional quantum simulation. Strong couplings between the IR-active proton-transfer motion and low-frequency, large-amplitude torsional modes are clearly identified, and their role in the cluster dynamics is explained. These couplings are responsible for the characteristic doublet at about 1000 cm−1.

    30. Recently Reported Crystalline Isothiazole Carbenes: Myth or Reality (pages 6922–6925)

      Alan DeHope, Vincent Lavallo, Bruno Donnadieu, Wolfgang W. Schoeller and Guy Bertrand

      Version of Record online: 27 JUL 2007 | DOI: 10.1002/anie.200702272

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      Singlet carbenes are not always stable: Isothiazole carbenes, recently reported as crystalline solids, cannot even be observed at room temperature; they rearrange into their 2-imino-2H-thiete isomers with an energy barrier of about 1 kcal mol−1 (see scheme). See also the following Correspondence.

  12. Correspondence

    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
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    1. Reply to “Recently Reported Crystalline Isothiazole Carbenes: Myth or Reality” (page 6926)

      Janine Wolf, Winfried Böhlmann, Matthias Findeisen, Thomas Gelbrich, Hans-Jörg Hofmann and Bärbel Schulze

      Version of Record online: 19 JUL 2007 | DOI: 10.1002/anie.200702746

      In light of the results of Bertrand and co-workers, the isothiazole carbenes previously reported by us cannot be considered to be stable. Evidently they are intermediates, which rapidly isomerize to the 2-imino-2H-thiete isomers. Nevertheless, it is possible to obtain their dimers and to postulate their contribution in the formation of morpholino or piperidino derivatives.

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    1. Top of page
    2. Cover Picture
    3. Inside Cover
    4. Editorial
    5. Graphical Abstract
    6. News
    7. Book Review
    8. Obituary
    9. Highlights
    10. Essay
    11. Review
    12. Communications
    13. Correspondence
    14. Preview
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